The present invention relates in general to manhole covers, and more particularly to a temporary manhole cover to be used while performing maintenance activities.
Manholes provide access to underground systems such as water and sewer utilities. Typically, they are covered with metal covers designed to withstand heavy weight loads, such as those from vehicles. The manhole cover is removed using a tool to gain access to the manhole. Typically, uncovered manholes are cordoned off during maintenance to avoid accidents. Temporary manhole covers are occasionally used to cover the manholes during maintenance to increase safety.
Several temporary manhole covers have been developed in art. For example, U.S. Pat. No. 6,893,186 to Tello discloses a temporary manhole cover for protecting workers purging a sewer line from splattering waste. The cover includes a substantially circular outer rim peripherally bordering a central indented portion and a pair of diametrically opposed handles positioned on the outer rim. The indented portion is preferably transparent to allow a worker to see into the manhole. An elongated opening extends from the center of the indented portion to the outer edge of the rim. A plurality of contiguous and intermeshing bristles are horizontally disposed within the opening. A water hose may be inserted through the bristles. The bristles prevent waste from exiting the manhole and assist in retaining the water hose at a desired position. The purpose and associated structures involved in viewing into the manhole and protecting workers from splattering waste of this cover are different from the present invention.
U.S. Pat. No. 5,529,431 to Walsh discloses a temporary manhole cover constructed of glass fiber reinforced polymeric plastic. The cover is an integral unit comprising a circular disc shape, an outer circular edge having a thickness, and a multiplicity of openings through a thickness of the disc shape spaced apart across the entire shape. The manhole cover also includes a cut out to the edge for pipes, tubing, and wires to be trained through the opening down the manhole. The manhole cover is strong enough to support a motor vehicle and light enough to be lifted out from below or above. Although the openings are similar, the present invention differs in that it comprises a different utility adapted for receiving maintenance tools.
Intl. App. No. JP2003105789 to Ishigaki discloses a temporary manhole cover having a disc-like cover body for blocking up an opening of the manhole disposed in the underground pipeline. The cover is provided with a penetrating hole to pass a blower pipe for feeding air into the underground pipeline, a plurality of light incident holes extending over the whole surface to make external light enter the underground pipeline, and an insert hole to handle the cover by inserting the hand. The disc-like structure and the configuration of the holes of this cover differ from the present invention.
Generally, valves of underground water utilities or other systems are accessed through the manholes, and maintenance workers have to climb down to operate them. A valve key tool, principally comprising an elongated rod, helps maintenance workers to operate the valves from the ground surface after opening the manhole cover. However, using the valve key from above an open manhole is hazardous for the workers in that there is a risk of falling into the manhole.
Therefore, it is an object of the present invention to provide a temporary manhole cover for use during operating valves of underground utilities.
A further object is to provide a temporary manhole cover that facilitates viewing into a manhole after installed thereon.
Finally, it is an object of the present invention to provide a temporary manhole cover that includes an adjustable mechanism for receiving and positioning a valve key. These and other objects of the present invention will become better understood with reference to the appended Summary, Description, and Claims.